#define _CRT_SECURE_NO_WARNINGS 
#include<stdio.h>

int Add(int x, int y)
{
	int z = x * y;
	return z;
}
int main()
{
	int i = 1;
	int static a = 1;
	int static b = 0;
	int n = 0;
	scanf_s("%d", &n);
	do
	{
	    b = Add(a, i);
		a = b;
		i++;


	} while (i <= n);
	printf("%d ", b);

	return 0;
}